U.S. patent number 4,577,179 [Application Number 06/367,867] was granted by the patent office on 1986-03-18 for programmer/timer for appliances.
This patent grant is currently assigned to Eaton Corporation. Invention is credited to Worthy L. Chambers, Arthur H. Hayden, William H. Jones.
United States Patent |
4,577,179 |
Chambers , et al. |
March 18, 1986 |
Programmer/timer for appliances
Abstract
A programmer timer (10) having motor driven cams (61, 64, 62,
66) for operating electrical switching mechanisms (102, 116, 144,
138, 126). The motor comprises a pair of spaced stator plates (24,
26) with a coil (34) and permanent magnet rotor (36) therebetween,
received in a walled chamber (28) in the timer housing. Motor
reduction gears (44) drive a shaft (48) for driving the ratchet
wheels (72, 68) and rotary cams. The motor, gear train cams and
electrical switching mechanisms are contained in a single integral
housing (12). Separate concentric fast and slow ratchet wheels (72,
68) are driven by a single eccentric driven pawl (14). The center
of rotation of the eccentric is positioned so that drive pawl
contacts the ratchet wheel at an angle at least 10.degree. greater
than a tangent at the contact point, for all eccentric positions,
to provide ratchet wheel advance in the event of reverse rotation
of the eccentric. A bifurcated anti-reverse pawl (84) is biased
against the fast and slow ratchet wheels by a spring arm (88)
integral therewith. The center of rotation of the eccentric is
spaced from the fast and slow ratchet wheel centers and optionally
has a subinterval cam (148) provided thereon for affecting
switching. The anti-reverse pawl may optionally be pivoted about
the center of rotation of the drive eccentric. The motor stator
plates optionally include integrally therewith a striker arm (178,
180) and anvil (176) for cam controlled operation of a buzzer. The
ratchet drive pawl alternatively is biased by a spring arm (154)
formed integrally therewith. The ratchet wheel may also optionally
employ wiper contacts (200) for contacting a stationary printed
circuit board.
Inventors: |
Chambers; Worthy L. (Lombard,
IL), Jones; William H. (Villa Park, IL), Hayden; Arthur
H. (Crystal Lake, IL) |
Assignee: |
Eaton Corporation (Cleveland,
OH)
|
Family
ID: |
23448965 |
Appl.
No.: |
06/367,867 |
Filed: |
April 15, 1982 |
Current U.S.
Class: |
340/309.8;
200/35R; 200/38R; 200/39R |
Current CPC
Class: |
H01H
43/102 (20130101) |
Current International
Class: |
H01H
43/10 (20060101); H01H 43/00 (20060101); G08B
001/00 (); H01H 007/08 () |
Field of
Search: |
;340/309.15,309.4,309.5
;307/140,141 ;74/116,118,122,125,568T,154
;200/38R,38B,38FA,38BA,38CA,35R,39R,3R ;310/68R,69 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Caldwell, Sr.; John W.
Assistant Examiner: Queen; Tyrone
Attorney, Agent or Firm: Grace; C. H. Johnston; R. A.
Claims
We claim:
1. A device for electrical switching in timed sequence
comprising:
(a) a primary and secondary cam means rotatably mounted on a
housing about respectively first and second spaced centers of
rotation;
(b) electrical switch means including primary cam follower means
responsive to movement of said primary cam means for effecting
electrical switching of contacts in accordance with a first program
sequence;
(c) secondary cam follower means responsive to said secondary cam
means for altering said electrical switching in accordance with a
second program sequence;
(d) ratchet and pawl means operative to cause rotation of said
primary cam means and including a ratchet wheel rotatable about
said first center and a drive pawl orbital about said second
center; and,
(e) drive means rotatable about said second center to cause said
pawl to index said ratchet.
2. A device for switching in timed sequence comprising:
(a) primary cam means including a ratchet wheel rotatably mounted
on a housing;
(b) primary cam follower means responsive to movement of said cam
means and operative for effecting movement of one of a first set of
electrical contacts;
(c) drive means for advancing said cam means said drive means
including;
(i) a drive pawl pivotally mounted on said housing about a point
spaced from the center of rotation of said cam means, said pawl
contacting said ratchet wheel;
(ii) eccentric means rotatable for driving said pawl;
(iii) sub-interval cam means mounted on said housing means for
rotation about a common center with said eccentric means;
(iv) motor means operative to rotate said sub-interval cam means
and said eccentric means for effecting movement of said pawl for
advancing said ratchet wheel;
(d) secondary cam follower means operative in response to rotation
of said sub-interval cam means to effect sub-interval movement of
one of said set of electrical contacts.
3. The device defined in claim 2, wherein:
(a) said primary cam follower means is operative to effect movement
of one of a first set of electrical contacts; and,
(b) said secondary cam follower means is operative to effect
movement of one of a second set of electrical contacts.
4. The device defined in claim 2, wherein, said secondary cam
follower means is operative to effect sub-interval opening and
closing of said set of contacts and said primary cam follower means
is operative to prevent movement of said contacts by said
sub-interval cam follower means during a primary interval.
5. The device defined in claim 1, wherein said pawl makes an angle
less than ten (10) degrees above the tangent to the ratchet point
of contact by the pawl.
Description
BACKGROUND OF THE INVENTION
The present invention relates to programmer timers for appliances
such as dishwashers, clothes washers, and clothes driers.
Appliances of this type commonly utilize a synchronous timing motor
to drive a cam mechanism for actuating a plurality of cam follower
actuated switches for making and breaking individual electrical
circuits for various control functions of the appliance.
Programmer-timers of this type operate to control the appliance
function in timed sequence and duration for providing a preselected
program cycle of appliance operation.
It is known to provide appliance programmer timers having a
plurality of rotary cams mounted for rotation about a common axis
with the cam being rotationally advanced by a stepping mechanism.
In programmer/timers of this known type, ratchet wheels are
provided for advancing the rotary cams and a motor driven
oscillating pawl engages the ratchet wheel for step-by-step
advancement of the cam. The advance pawl may be driven by a
rotating eccentric or crankshaft attached to a suitable gear
reduction mechanism driven by the synchronous timing motor.
Known programmer/timers employing a synchronous timing motor have
employed a ratchet mechanism in the synchronous motor to prevent
reverse rotation startup of the motor which is an inherent feature
of a synchronous motor. This antireverse feature in the motor has
been necessitated in order to prevent reverse rotation of the drive
mechanism for the ratchet advance pawl. Where the ratchet advance
pawl is driven by a rotating crank or eccentric, reverse rotation
of the eccentric has caused the drive pawl to "kick out" or
disengage from the ratchet teeth and thereby malfunction in
advancing the cam.
In programmer/timers for appliances, it is known to provide axially
adjacent ratchet wheels having different pitch diameters for the
peripheral teeth thereof but utilize the same pitch for the teeth
of both wheels in order that a single drive pawl may actuate both
ratchet wheels. It is also known to provide an intermittent series
of deeper notches on one ratchet wheel to permit the drive pawl to
periodically advance the first and second ratchet wheels together
for a single step. This arrangement provides for faster advancement
of the cam attached to the ratchet having the greater tooth pitch
diameter than the cam attached to the second ratchet wheel.
Moreover, it has been desired to provide a programmer timer having
a convenient low cost means for providing actuation of a separate
cam follower at sub-intervals of advancement of the main ratchet
wheel. Sub-interval cam follower actuation may then be employed to
modify the actuation of a set of contacts actuated by either the
fast or slow cam wheel or to actuate a separate set of electrical
contacts.
Appliance programmer/timers have heretofor employed a separate
timing motor attached to a housing which contained the escapement,
cams, cam followers and electrical contacts. The gear reduction
mechanism for driving the escapement has heretofore usually been
incorporated in the separate motor housing. This arrangement
permits separate assembly of the motor and timer mechanism;
however, such an arrangement has the disadvantage of increased cost
associated with separate housings for the motor and the timer
mechanism.
Thus, it has been desired to provide an appliance programmer timer
having a synchronous motor driven cam advance mechanism which
eliminates the need for an anti-reverse directional ratchet
mechanism on the timing motor and accommodates rotation of the
timing motor in either direction without malfunction of the
escapement. It has further been desired to provide a low cost
programmer timer with the motor and timer assembled as a unit in an
integral housing thereby eliminating the need for separate motor
and timer housings. It has further been desired to provide a simple
and low cost programmer timer having a sub-interval timed
electrical switching function with relation to the timing interval
employed by the main switching sequence.
SUMMARY OF THE INVENTION
The present invention provides an appliance programmer timer having
an escapement driven by a synchronous motor for advancing a rotary
cam having a follower for actuating a set of electrical contacts to
perform a switching function. The present invention employs an
eccentric driven advance pawl contacting a ratchet wheel connected
to the rotary cam for providing step-by-step advancement of the
cam. The axis of rotation of the eccentric is spaced from the axis
of rotation of the cam and has mounted for rotation therewith a
sub-interval cam. A separate cam follower is responsive to rotation
of the sub-interval cam to alter the movement of the electrical
contacts or, alternatively, actuate a separate set of electrical
contacts.
The programmer timer of the present invention employs a unique
integral timer-motor housing wherein the motor comprises a pair of
spaced parallel stator plates received in a walled cavity in the
housing and registered for alignment therein with the motor coil
and rotor disposed between the parallel stator plates. The present
invention employs the motor described in copending application Ser.
No. 260,626 filed May 5, 1981 entitled "Synchronous Motor", now
abandoned, and assigned to the assignee of the present invention.
The housing in one embodiment of this arrangement has a deck, or
wall, portion separating the motor for the gear reduction, cams,
escapement, cam followers and electrical contacts. The arrangement
thus permits assembly of the motor on one side of the housing and
assembly of the escapement, cams and contacts on the other side of
the housing to thereby provide a unified assembly of the programmer
timer and minimize manufacturing costs. An alternate embodiment of
the integral housing for the motor and timer permits the motor,
cams, contacts and escapement to be assembled from one side of the
housing.
The cam advance escapement in the present invention employs an
eccentric driven pawl which engages the ratchet wheel or wheels
such that the direction of motion of the pawl forms an angle with
the tangent to the ratchet, at the point of contact, of not less
than 10.degree.. This arrangement of the pawl and ratchet permits
the pawl to advance the ratchet wheel normally even if the
eccentric pawl drive mechanism is rotated in a reverse manner by
synchronous timing motor.
The present invention thus provides a unique and low cost
programmer timer having a novel means for providing timed interval
switching functions and sub-interval switching functions and
accommodates forward and reverse rotation of a synchronous timing
motor without malfunction. The present invention also employs a
unique arrangement of the synchronous timing motor and timer
housing to permit assembly of the motor and timer mechanism in a
unified housing arrangement.
The cam advance mechanism of the present invention employs a unique
anti-reverse pawl biased against the cam advance ratches by an
integral spring finger. The present invention optionally employs a
unique integral spring-ratchet pawl for preventing the operator
from manually reversing the cam and advance ratchet during program
selection. The escapement of the present invention optionally
employs a ratchet advance pawl having an integral spring finger for
biasing the pawl against the ratchet. Another optional feature
provides a unique alarm buzzer formed integrally with the motor
stator plates.
A BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of the programmer/timer of the present
invention with the housing cover removed for purposes of
illustration;
FIG. 2 is a section view taken along section-indicating lines 2--2
of FIG. 1;
FIG. 3 is a view taken along section-indicating lines 3--3 of FIG.
1;
FIG. 4 is a section view taken along section-indicating lines 4--4
of FIG. 1 and shows the motor and gear reduction installed in the
integral housing;
FIG. 5 is a portion of a view similar to FIG. 1 and shows an
alternate embodiment of the escapement;
FIG. 6 is a portion of a view similar to FIG. 1 and shows another
embodiment of the escapement;
FIG. 7 is a portion of a view taken along section-indicting lines
7--7 of FIG. 4 and shows the optional buzzer;
FIG. 8 is a partial view taken along section-indicating lines 8--8
of FIG. 7;
FIG. 9 is a partial view taken along section-indicating lines 9--9
of FIG. 8;
FIG. 10 is a partial view similar to FIG. 4 and illustrates an
alternate embodiment employing a stationary printed circuit board
having rotating wipers for auxiliary switching functions and an
alternate housing arrangement for the motor and timer
mechanism;
FIG. 11 is a partial view taken along section indicating lines
11--11 of FIG. 10;
FIG. 12 is a partial plan view taken along section-indicating lines
12--12 of FIG. 10 illustrating an optional push-to-start switch
feature;
FIG. 13 is a partial view taken along section-indicating lines
13--13 of FIG. 12;
FIG. 14 is a partial section view taken along section-indicating
lines 14--14 of FIG. 1; and
FIG. 15 is a portion of a plan view of an alternate arrangement of
the embodiment of FIG. 1.
DETAILED DESCRIPTION
Referring now to FIGS. 1, 2, 3 and 4, the programmer timer of the
present invention is indicated generally at 10 as having a housing
12 having formed integrally therewith (see FIG. 4) a timer cavity
14 and a motor cavity 16 which are separated by a dividing wall
portion 18. The timer cavity 14 has a cover plate 20 received
thereover and retained by a suitable means, such as snap locks 22,
formed integrally with the housing 12. The timer cavity 14 is shown
in plan view in FIG. 1 with the cover plate 20 omitted for
clarity.
The motor cavity 16 has received therein a pair of spaced motor
stator plates 24, 26 which are registered against the inner
periphery of the cavity wall 28 and received over a plurality of
shouldered posts shown typically at 30. The stator plates are
retained thereon by suitable fasteners such as clips 32. A motor
coil assembly, indicated generally at 34, is received between the
stator plates in side-by-side relationship with a permanent magnet
rotor assembly, indicated generally at 36, having axle pin 38
journaled at its upper end in housing wall 18 and in stator plate
26 at its lower end. A plurality of interdigitated stator poles 40
are formed integrally in the stator plates and surround the rotor
assembly. A suitable ferromagnetic core 42 is provided for
completing the flux path between the stator plates to permit
synchronous operation of the motor.
Stator plate 24 is spaced from the housing wall 18 by an amount
suitable to permit the incorporation of a gear train, indicated
generally at 44, which is driven by rotor pinion 46 which extends
through an aperture in stator plate 24 and is attached to the rotor
36. The output of the gear train 44 is through shaft 48 journaled
for rotation on a post 50 formed on the housing wall 18 which post
50 extends upward into timer cavity 14. Shaft 48 has an eccentric
52 provided thereon and has its upper end journaled for rotation in
aperture 54 provided in the housing cover 20.
A timer cam wheel 56 is received in timer cavity 14 and has a stub
shaft 58 journaled in an aperture formed in housing wall 18 and
spaced from the center of rotation of shaft 48. Wheel 56 also has a
shaft 60 extending therefrom in a direction opposite stub shaft 58
and through an aperture in housing cover 20. Shaft 60 is adapted
for manual rotation by the appliance operator for suitable cycle
program selection. In the presently preferred practice wheel 52 has
a plurality of peripheral cam tracks 61, 64 and 66 provided thereon
and has concentric therewith and axially adjacent a toothed ratchet
surface 68 provided about the periphery thereof. A second ratchet
wheel 70 is received over shaft 60 for free rotation with respect
to wheel 56 and wheel 70 also has a toothed ratchet surface 72
provided about the periphery thereof.
Eccentric 52 has one end of a drive pawl 74 received thereover for
reciprocal (orbital) movement thereof upon rotation of shaft 48.
The free end of pawl 74 has a ratchet engaging tooth 76 provided
thereon which tooth is sufficient in width to engage both ratchet
68 and ratchet 72.
Referring in particular to FIG. 1, the teeth of ratchet 72 has a
pitch diameter slightly larger than ratchet 68. In the presently
preferred practice ratchet 72 intermittently contains a deep notch
78 at a desired interval, or multiple or teeth, such that upon the
pawl tooth 76 engaging the deep notch, pawl 74 drops to a position
whereupon the ratchet tooth 76 engages simultaneously ratchet 72
and ratchet 68 to thereby index both ratchet wheels together for a
single stroke. Thus, the single pawl 74 provides continuous
indexing of wheel 70 and intermittent indexing of wheel 56,
dependent upon the number and spacing of deep notches provided in
ratchet 72.
With continuing reference to FIG. 1, gear box output shaft 48
rotates about a center of rotation "A" and eccentric 52 is
eccentric to point "A". In the presently preferred practice, the
eccentric drive surface 52 is formed by a circular surface on shaft
48 having a center of rotation "C" displaced from shaft center "A"
by an amount equal to the dimension "B". The indexing mechanism
thus yields a longitudinal stroke for pawl 74 equal to twice the
amount of "B".
In order for the drive pawl 74 to function properly, irrespective
of the direction of rotation of eccentric 52, it is necessary that
the angle of contact of drive pawl 74 with the ratchets 72, 68 be
greater than a tangent angle to the ratchet at the point of contact
of pawl tooth 76. This is illustrated in FIG. 1 wherein a line
through the center of excursion "C" of eccentric 52 is shown to
make an angle 0 with the tangent to the ratchet at the point of
contact of pawl tooth 76.
In order to prevent pawl tooth 76 from disengaging or "kicking out"
of the teeth of the ratchet, for all positions of center of
excursion "C" of eccentric 52, it is necessary that the angle 0 be
approximately 10 degrees or greater. This means that for all
positions of center of excursion "C" as eccentric 52 rotates either
clockwise or counterclockwise, a line through center "C" and the
point of contact of pawl tooth 76 with the ratchet must make an
angle of at least 100 degrees with a radius to the ratchet at the
point of tooth contact. The "bite" of pawl tooth 76 is maximized
when the driving stroke occurs with center of excursion "C" of
eccentric 52 above the center of rotation "A" of shaft 48, as
viewed in FIG. 1.
The arrangement for the indexing mechanism shown in FIG. 1 gives
the pawl tooth 76 sufficient "bite" on the ratchet teeth to prevent
malfunction of pawl 74 in the event of counterclockwise rotation of
eccentric 52, it being understood that in normal operation
eccentric 52 rotates in a clockwise direction as viewed in FIG. 1
in order to maximize the "bite" of the pawl tooth 76.
Referring now to FIGS. 1 and 2, an antireverse pawl having hub 80
is pivotally received over a mounting post 82 extending from the
wall 18 of the timer housing. Pawl 80 has a pair of generally
parallel spaced fingers 84, 86 extending from the hub thereof with
pawl 84 contacting a larger diameter ratchet 72 and finger 86
contacting smaller ratchet 68 such that any attempt to rotate the
ratchets counterclockwise as shown in FIG. 1 would be resisted by
the "bite" of the fingers 84, 86 sufficient to prevent
counterclockwise rotation of the ratchet.
Pawl 80 has a third finger 88 formed integrally with the hub 80 and
extending rightwardly in FIG. 1 which registers against a
shouldered portion 90 provided integrally in the housing wall 18.
In the presently preferred practice, the pawl finger 88 is formed
of resilient material such that it comprises a spring preloaded
against lug 90 to provide torque on pawl hub 80 to thereby bias the
pawl fingers 84, 86 into contact with ratchets 68, 72. It will be
understood however to those skilled in the art that although pawl
finger 88 is formed of rigid material in the embodiment described,
fingers 84, 86 may alternatively be formed of resilient material to
thereby provide a preload of the fingers against the ratchet
teeth.
Alternatively, as will hereinafter be described, antireverse pawl
80 may be pivotally mounted about the center of rotation "A" of
drive shaft 48 to give the antireverse pawl and the main drive pawl
74 a common reference point for attacking the ratchet teeth.
Functionally, this alternate arrangement facilitates varying the
stroke of the advance pawl 74 and yet permits the antireverse pawl
to properly engage the ratchet teeth irrespective of the stroke of
the advance pawl.
Referring again to FIG. 1, the slower or main ratchet 68 can
optionally have a raised tooth portion 92 having the same tooth
pitch and pitch diameter as the teeth of ratchet 72 such that, at a
selected position on the program cam wheel 56, the drive pawl tooth
76 engages raised tooth 92 to provide a single one-step advance of
the wheel 56 at a position separate from the deep notches 78.
Referring now to FIGS. 1, 3 and 4, the main or slow ratchet wheel
56 has the cam track 61 thereof engaged by a cam follower 94 having
a cam engaging tooth 96 and being pivotally mounted about a post 98
extending upwardly from the wall 18 of the timer housing. Track 62
of the cam wheel 56 is engaged by cam follower 100 having a cam
engaging tooth 102 with the follower 100 pivoted about post 82 (see
also FIG. 2). Cam track 64 is engaged by tooth 104 provided in cam
follower 106 pivotally received over post 98. Cam track 66 is
engaged by tooth 108 of cam follower 110 which is pivotally mounted
about post 82 (see FIG. 2).
Cam follower 94 has formed integrally therewith a lug 112 operative
to contact for movement an electrical switch contact arm 114 having
a movable contact 116 provided thereon for alternately making and
breaking a circuit with stationary contacts 118, 120.
Cam follower 100 has a lug 122 extending integrally therefrom which
contacts a movable electrical switch arm 124 having a movable
contact 126 provided thereon. Lug 122 is operative upon movement of
the follower 100 to move contact 126 alternately between stationary
contacts 128, 130 for making and breaking electrical contact
therebetween as desired for the appliance cycle program.
Cam follower 106 has a lug 132 extending integrally therefrom which
upon motion of follower 106 contacts a movable contact arm 134
having a movable contact 136 provided thereon for making and
breaking electrical contact with a stationary contact 138.
Cam follower 110 has an integral lug 140 extending therefrom
operative to contact a movable switch arm 142 having a movable
contact 144 provided thereon for making and breaking an electrical
circuit with stationary contact 146.
The programmer/timer of the present invention thus provides in the
embodiment of FIGS. 1 and 4 a fast and slow ratchet operative to
drive a main cam wheel 56 and a secondary cam surface 70 (see FIG.
4) attached to the fast ratchet 72. In the embodiment of FIG. 1,
cam follower tooth 102 on cam follower 100 has sufficient width to
ride the track of cam 70 on the fast ratchet wheel so as to be
responsive to notches thereon for permitting contact of movable
electrical contact 126 with stationary contact 130 as required by
the appliance cycle program.
It will be understood to those skilled in the art however, that as
between cam track 70 and cam track 62, the sequence of events and
positioning contact 126 by contact of the cam follower lug 122 with
arm 124 may vary as desired to provide numerous combinations. For
example, movable contact 126 may generally be positioned
intermediate contacts 128 and 130 by cam track 62 and operative
thereby to intermediately make contact with stationary contact 130;
and, responsive to cam track 70 on the fast ratchet wheel to make
contact with contact 128 or to periodically make a circuit with
stationary contact 130.
Alternatively, cam track 70 may be employed to make a circuit with
stationary contact 130 and cam 62 may be employed only to make and
break a circuit with contact 128. The particular choice of
sequencing of contacts 126, 128 and 130 responsive to cam tracks 62
and 70 will be governed by the requirements of the program cycle of
the particular appliance.
Referring now to FIG. 5, an alternate embodiment, indicated
generally at 10', of the timer of FIG. 1 is shown wherein the shaft
48 about which eccentric 52 rotates, has an auxiliary cam track 148
provided thereon for rotation with shaft 48 about point "A". A
drive pawl 150 has one end thereof received over eccentric 52 for
orbital movement therewith and has a drive tooth 152 formed
integrally therewith for engaging the ratchet on wheel 56. Pawl 150
has formed integrally therewith a resilient spring member 154 which
extends from the pivot center "A" in a direction opposite of pawl
150; and, finger 154 is registered against a lug 156 provided
integrally from housing wall 18. The finger 154 is preloaded by an
amount to sufficient provide the necessary bias to maintain the
drive pawl tooth 152 in engagement with the ratchet.
A cam follower 158 is pivotally mounted about a post 160 extending
from the housing wall 18. Cam follower 158 has a portion extending
from post 160 in a direction opposite the cam track 148 which
portion has a lug 162 formed thereon for contacting the movable
contact arm 124. In operation, as drive shaft 48 rotates, cam track
148 causes cam follower 158 to pivot which in turn causes lug 162
to move the contact 126 toward and away from stationary contact
130. The cam track 148 thus operates as a subinterval cam for
movement of the movable electrical contact 126 with respect to the
main interval operation of contact 126 by cam follower lug 122.
Referring now to FIG. 6, another alternate arrangement of the timer
of FIG. 1 is indicated generally at 10" wherein a main drive pawl
164 is pivotally received over eccentric 52 which is driven by
shaft 48 by rotation about pivot center "A" for orbital movement of
the pawl 164. Integral drive tooth 166 on pawl 164 contacts the
ratchet on wheel 56 for causing indexed movement thereon. Shaft 48
also has auxiliary cam 148 provided thereon for movement of cam
follower 158 for effecting subinterval movement of contact 126 in
similar fashion to the embodiment of FIG. 5.
In the embodiment of FIG. 6, the main drive pawl 164 preferably has
an integral spring finger 168 extending outwardly from the end of
drive pawl 164 containing ratchet contacting tooth 166. Spring
finger 168 is registered against a stationary lug 170 extending
from the wall 118 of the timer housing. The spring finger 168 is
preloaded by a desired amount to provide suitable bias of the pawl
tooth 166 into contact with the ratchet wheel.
Referring again to FIG. 1, a still further alternate embodiment of
the stepping mechanism of the present invention is illustrated
wherein the drive pawl 74 has an arm portion 172 extending
therefrom in a direction angularly spaced from arm 74 with one end
of a preload spring 174 connected thereto. The opposite end of
spring 174 is anchored to a stationary post 176 extending from the
wall 18 of the timer housing such that spring 174 is tensioned to
provide a preload of pawl arm tooth 76 against the ratchet on wheel
56.
Referring now to FIGS. 7, 8 and 9, an optional buzzer is
illustrated as formed integrally with the motor stator plates in
the timer construction of the present invention.
As illustrated in FIG. 7 the outer stator plate 26 has formed
integrally with one edge thereof an anvil 176; and, as shown in
FIG. 8 a striker arm 178 is formed integrally with one edge of the
opposite stator plate 24, with the striker 176 extending in the
free position in spaced parallel arrangement with striker 178.
The striker arm 178 has a cam follower portion 180 formed preerably
integrally therewith and extending therefrom through an aperture
182 formed in the wall 18 of the timer housing. The cam follower
portion 180 makes contact with one of the cam tracks on main cam
wheel 56 as for example, cam track 66.
In operation, when the cam track 66 releases cam follower 180 from
a position biased away from anvil 176, the alternating current
excitation of the magnetic field in stator plates 24, 26 causes the
striker arm 178 to vibrate against anvil 176 thereby giving an
audible alarm.
Referring now to FIG. 10, an alternate embodiment of the timer of
FIG. 1 is indicated generally at 190 as having a unitary housing
192 having a deep-well configuration with wall 194 about the
periphery thereof and open to one side. Motor plates 24, 26 are
received therein in spaced parallel arrangement, with the rotor
assembly indicated generally at 36 and coil assembly indicated
generally at 34 received therebetween with the stator plates
received over posts shown typically at 193 and retained thereon by
clips 32.
In the embodiment of FIG. 10, the gear train indicated generally at
196 is assembled into the housing 192 for the opened side thereof,
the motor stator plates, rotor and coil are assembled therein and
the fast ratchet wheel 197 and slow or ratchet and wheel 195
containing the four main cam tracks are then assembled into the
housing in side-by-side arrangement with the motor stator plates as
shown in FIG. 10.
The escapement mechanism and contact arms are also assembled into
the housing 192 from the open side thereof and a cover plate 198 is
then secured thereover.
Referring now to FIGS. 10 and 11, the main cam wheel has a
plurality of rotating wiper arms 200 secured thereto by suitable
fasteners such as rivets 202 and the wiper arms contact a
stationary printed circuit board 204 secured to the inside of a
cover plate 198. Thus the embodiment of FIG. 10 employs additional
switching functions on the same cam wheel by incorporating rotating
wipers for switching between contacts provided on a stationary
printed circuit board. It will be understood however that
alternatively, the printed circuit board 204 may be secured to the
rotating cam wheel 195 and the wipers 200 may be secured in a
stationary manner to the inside of housing cover plate 198.
Referring now to FIGS. 10, 12 and 13, the push-to-start feature of
the timer 190 is illustrated wherein the main shaft 206 for cam
wheel 195 may be pushed axially by the appliance operator from the
position shown in solid outline in FIGS. 10 and 13 to the position
shown therein in dashed outline. The shaft 206 has a circular cam
surface 208 provided thereon adjacent the end nearest the wall 192
of the housing and a slidable cam follower 210 is engaged by the
cam surface 208. A movable contact arm 212 having a movable
electrical contact 214 thereon registers against cam follower 210
and has the stationary end thereof connected to an electrical
connecting terminal 216 which extends to the exterior of the
housing.
A stationary electrical contact 218 is attached to one end of an
electrical connecting terminal 220 which also extends through the
wall 192 of the housing for external attachment thereto. In
operation, as the shaft 206 is moved axially by the operator to the
position indicated in dashed outline, cam surface 208 moves
follower 210 which causes arm 212 to move stationary contact 214 to
make electrical connection with contact 218 to complete the circuit
to the power source for energizing machine operation.
By pushing the shaft 206 the appliance operator can complete the
line power circuit irrespective of the position of the rotary cam
wheel 195. Thus, the timer motor may be energized irrespective of
the position of the electrical switching contacts associated with
the cam wheel 195 and the cam wheel 197.
The embodiment of FIG. 10 permits assembly of the motor, gear
train, stepping mechanism, rotary cams and ratchet wheels and cam
followers and contacts all from one side of the timer housing
without reversing the position of the timer housing during
assembly. The additional advantage of the embodiment of FIG. 10 is
that the gear train 196 may be assembled in the housing without the
power output shaft thereof extending through the wall of the
housing. The embodiment of FIG. 10 also eliminates the need for
journaling one end of the output shaft in the cover of the timing
housing as is the case in the embodiment of FIG. 4.
Referring now to FIG. 14, the arrangement of a typical contact arm
with integral electrical connecting terminals is shown, wherein a
an arm portion 222 (see FIG. 1) has a folded double thickness
portion 224 provided thereon and extending at right angles from
portion 222. The folded portion 224 extends through an aperture 226
provided in the wall 18 of the housing and is adapted for external
electrical connection thereto. The folded portion 224 of the arm
222 is received in a slot formed by spaced guide surfaces 228, 230
formed integrally with a raised portion indicated generally at 232
provided in the timer housing. The arrangement of FIG. 14 thus
provides a unitary electrical connecting terminal and contact arm
arrangement which is retained by simple sliding engagement with
guide surfaces formed in the timer housing.
Referring now to FIG. 15, an alternate arrangement of the
embodiment of FIG. 1 of the invention is shown wherein the
antireverse member 222 is received on shaft 48 for pivotal movement
about the center of rotation "A" of shaft 48. Member 222 has a pawl
finger 224 which engages the ratchet 68 for preventing reverse
rotation thereof by the appliance operator. Member 222 preferably
has a resilient spring finger 226 provided integrally therewith
which spring finger is registered against a lug 228 extending from
the wall 18 of the housing. The spring finger 226 is preloaded to
bias the pawl 224 into engagement with the ratchet 68. The
arrangement of FIG. 15 thus provides a common pivot reference for
the main drive pawl and the antireverse member.
The present invention thus provides a unique appliance
programmer-timer having a motor and cam driven electrical switching
mechanism assembled in a unitary housing. The programmer-timer of
the present invention employs a stepping mechanism for advancing
the electrical switching cams. The stepping mechanism employs an
eccentric-driven advancement pawl for indexing a ratchet wherein
the advancement pawl will accommodate reverse rotation of the
driving eccentric without malfunction of the advance mechanism. The
timer of the present invention employs a unique antireverse ratchet
pawl having an integral bias spring for preventing reverse rotation
of the programming cam by the appliance operator. Optional features
of the programmer-timer of the present invention include an
auxiliary subinterval cam provided on the shaft driving the
eccentric for the advance pawl and an optional buzzer having a
striker and anvil formed integrally with the motor stator plates.
The present invention employs an optional drive pawl having
integral bias spring finger formed therewith. An optional rotating
printed circuit board-wiper arrangement is provided for the cam
wheels for additional switching functions.
Although the invention has hereinabove been described in the
presently preferred practice, it will be understood by those having
skill in the art, that the invention is capable of modifications
and variations all of which are deemed to be encompassed by the
invention as defined by the following claims.
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